1. Field of the Invention
The present invention relates to an intake port of an internal combustion engine (hereinafter referred to as an xe2x80x9cenginexe2x80x9d).
2. Description of the Related Art
In direct injection type engines which directly inject fuel into the combustion chamber from a fuel injector, it is known to improve the degree of mixing of the fuel and air in the combustion chamber by making the air flow into the combustion chamber so that it swirls in the chamber. This type of engine is disclosed in Japanese Unexamined Patent Publication (Kokai) No. 8-42390.
In the above direct injection type engine, however, the greater the number of times the air swirls in the combustion chamber per unit engine speed (hereinafter referred to as the xe2x80x9cintake swirl ratioxe2x80x9d), the higher the degree of mixing in the combustion chamber. Therefore, in Japanese unexamined Patent Publication (Kokai) No. 8-42390, to increase the intake swirl ratio as much as possible, the wall of the engine defining the intake port is given an edge extending in a direction perpendicular to the air flowing through the intake port, that is, in the horizontal direction with respect to the air flowing through the intake port. Japanese Unexamined Patent Publication (Kokai) No. 8-42390 explains that this edge causes the air to concentrate at a specific region and then flow into the combustion chamber, so the intake swirl ratio becomes larger.
In this way, in direct injection type engines, there are demands for increasing the intake swirl ratio as much as possible. In general, however, if increasing the intake swirl ratio by causing the air to concentrate at a specific region as explained above, part of the space in the intake port near the combustion chamber will no longer be able to be used for the flow of air. The total amount of the air taken into the combustion chamber will therefore end up being reduced by the amount of that space. That is, increasing the intake swirl ratio and increasing the total amount of the air taken into the combustion chamber are generally contradictory.
An object of the present invention is to increase the swirl ratio of air taken into the combustion chamber of an engine chamber as much as possible while maintaining a large total amount of air taken into the chamber.
To attain the above object, according to a first aspect of the present invention, there is provided an intake port of an internal combustion engine having an intake passage curved to a certain direction and communicated with a combustion chamber of the engine to send air into the combustion chamber, provided with a groove provided in a wall at a side near a center of curvature of said intake passage in the wall defining the intake passage and extending along the flow of air in the intake passage, at least one long edge formed by one side wall of the wall defining said groove and the wall adjoining said side wall in the wall defining the intake passage, extending along the flow of air in the intake passage, and projecting out toward the inside of the intake passage, and a bent part provided at the wall of the side near the center of curvature of the intake passage in the wall defining the intake passage in proximity to a line connecting the intake passage and combustion chamber and extending in a horizontal direction with respect to the flow of air in the intake passage.
According to this, due to the provision of the long edge, the total amount of air taken into the combustion chamber becomes greater. Further, since the intake passage is communicated with the combustion chamber while being curved in a certain direction, the air flowing through the inside of the intake passage flows into the combustion chamber while being concentrated at a specific region and swirls in the combustion chamber. Since the bent part is provided, the air flowing through the intake passage flows into the combustion chamber while being further concentrated at a specific region, so more powerfully swirls in the combustion chamber. That is, the swirl ratio of the air in the combustion chamber becomes larger.
Preferably, the bent part is formed by the boundary of said groove at the combustion chamber side.
Preferably, the at least one long edge comprises two long edges formed by the two side walls in the wall defining the groove and the walls adjoining these side walls in the wall defining the intake passage, extending along the flow of air in the intake passage, and projecting out toward the inside of the intake passage. The distance between the long edges at the side near the combustion chamber is longer than the distance between these long edges at the side far from the combustion chamber.
Preferably, the bottom wall in the wall defining the groove is flat.
Preferably, at least part of the wall at the side far from the center of curvature of the intake passage in the wall defining the intake passage is flat.
According to a second aspect of the present invention, there is provided an intake port having an intake passage for sending air into a combustion chamber of an internal combustion engine and having a long axis of said intake passage extending toward a partial region of the intake port of the combustion chamber opening when an intake valve opens, provided with a groove provided in the wall of a side different from a wall facing the partial region of said intake port when viewed along a long axis of said intake passage in the wall defining the intake passage and extending along the flow of air in the intake passage, a long edge formed by one side wall of the wall defining the groove and the wall adjoining said side wall in the wall defining the intake passage, extending along the flow of air in the intake passage, and projecting out toward the inside of the intake passage, and a bent part provided at the wall of the side where said long edge is provided in the wall defining the intake passage in proximity to a line connecting the intake passage and combustion chamber and extending in a horizontal direction with respect to the flow of air in the intake passage.
According to this, due to the provision of the long edge, the total amount of air taken into the combustion chamber becomes greater. Further, since the long axis of the intake passage extends toward a partial region of the intake port of the combustion chamber when the intake valve is opened, the air flowing through the inside of the intake passage flows into the combustion chamber while being concentrated at a specific region and swirls in the combustion chamber. Since the bent part is provided, the air flowing through the intake passage flows into the combustion chamber while further being concentrated at a specific region, so more powerfully swirls in the combustion chamber. That is, the swirl ratio of the air in the combustion chamber becomes larger.